I had five of the 24-70 f/2.8 MkI lenses over a period of years. I'm sure I was spectacularly unlucky but they were all dogs. Apparently there are good copies out there. After a 48 hour test drive of the new lens I have to say I was gobsmacked. The new lens is in another galaxy. It was sharp everywhere at f/2.8. It matches my 24 f/1.4II prime at f/2.8. The new lens beats the old lens in all respects so comprehensively it's ridiculous. If only they were the same price. But even at $2300 I see this lens as a great buy. It's just that good.

Don't Q&A about this. As the Nike marketing people are so fond of saying...Just Do It.

Rent the 24-70mm first, before selling your 28-70mm. The two lenses are different, with the 24-70mm Mk.II not necessarily being better in all aspects. I've used both and preferred the 28-70mm for its deep saturated colours. (And sharpness isn't all and everything.)

Logged

Happily ignoring the laws of physics and the rules of photography to create better pictures.

How much of an improvement will I get? A quantified statement with specifics would be useful.

I tried 2 dif 24-70 f2.8 II from Crutchfield. The sharpness from both lenses were above 950 with Reikan FoCal - sharpness values were recorded at f2.8. If you step down to f4 - 5.6, I have no doubt the sharpness would be way above 1000 to 1100ish. Which, better than most Canon L primes.

Also, your 28-70 Mk I has a similarly large hood as my 24-70L Mk I -- one that does not move with zooming. This allows for optimal shading for any focal length. The 24-70L II has the 24-105L style smaller hood which only covers you at the wide end. From Bryan Carnathan @ TDP:

"The 24-70 L II is nicer to use with the much smaller Canon EW-88C Lens Hood (included) in place and it stores more compactly. The lens is also much easier to grasp with the hood in reversed position. The downside is that the 24-70 L II's hood only properly shades the front element at 24mm. A much larger hood is needed to shade this lens at 70mm.

The 24-70 L I and 28-70 L retract deep into their main-lens-barrel-mounted hoods as their focal length is increased, they have significantly better shading at the longer focal lengths. In other words, the 24-70 L I and 28-70 L are using an appropriate-for-the-selected-focal-length lens hood at all focal lengths while the 24-70 L II (and most other similar zoom lenses) are using a made-for-24mm hood at all focal lengths."

I'm on the fence with this as well. My current 24-70L v1 has become an expensive paper weight (I have 16-35, 50, 85, and 70-200 2.8 non-IS). I am considering selling my 24-70 and my 70-200 in favor of the 70-200IS v2, but am a little worried that if I make the move I will miss the versatility in the 24-70 range....